A generic active strut with a vertical adjustment means is shown by DE 10 2005 053 493 A1. It discloses that the threaded spindle of a ball screw drive, which spindle is driven by way of an electric motor actuator, is pivoted to be axially immovable by way of two anti-friction bearings on a body-mounted guide sleeve and axially adjusts a ball screw nut which in turn vertically adjusts the adjustable spring plate of the support spring of the wheel suspension.
Between the vehicle body and the active strut there is a damper bearing which here is an elastomer bearing in a rubber-metal execution. The damper bearing eliminates high frequency vibrations which would otherwise travel from the roadway via the running gear into the body. Moreover, roadway impacts are reduced, such as, for example, when driving over obstacles and sections of bad road, potholes, etc. The damper bearing is therefore designed according to special characteristics, for example, a progressive spring characteristic, as a result of which the damper bearing hardens as the spring path increases.
The damper bearing accommodates the universal motion which is impressed on the strut by the kinematics of the wheel guiding elements. The force/moment is transmitted to the strut here via the joining site between a support rod and the strut. Thus, the entire damper is deflected in operation, the load moment and opposing force on the clamping of the piston rod being accommodated. Since the forced damper bearing already offers considerable resistance to deformation, the piston rod necessarily bends. In this way the section of the threaded spring which projects freely over the cylinder tube of the shock absorber can disadvantageously come into contact with the oscillating damper as a result of the kinematics-induced impressed forces in the shock absorber.